1. Field of the Invention
The present invention relates to a fastener stringer for a slide fastener for use in stretchable clothes such as sporting clothes, and more particularly, to a fastener stringer for a slide fastener whose element attaching portion is stretchable and which is capable of preventing breaking of its chain even when the element attaching portion is stretched.
2. Description of the Related Art
Conventionally, a slide fastener has been used in fashion clothes and underwear, and a number of slide fasteners have been used in stretchable clothes such as knit fabric clothes and sporting clothes. There is a need to attach a slide fastener for use in various kinds of stretchable clothes to such clothes with an excellent appearance and further cause the slide fastener to correspond to stretching or contraction of the clothes. For this reason, when the slide fastener tape is woven or knitted, its weaving structure or knitting structure or a material of a composition yarn or the like is selected so as to provide the fastener tape with stretching property. Further, it has been well known that the appearance of the slide fastener is better when it is formed with a woven fastener tape than when with a knitted fastener tape.
In the slide fastener for use in the stretchable clothes described above, its fastener tape is provided with stretching property in a tape longitudinal direction, for example. In this case, generally, the element attaching portion which is formed on one side edge of the fastener tape and on which fastener elements are to be attached is constructed so as not to be stretchable although the tape main body of the fastener tape is provided with appropriate stretching property in the tape longitudinal direction.
The reason will be described below. For example, if the element attaching portion of the fastener tape is stretched when the tape main portion and the element attaching portion of the fastener tape are provided with stretching property, a fastener element row attached to the element attaching portion is also stretched. Thus, when the fastener tape is stretched in a state in which right and left fastener element rows engage each other, the fastener element rows are stretched over a certain extent in the tape longitudinal direction, which causes a fault called breaking of chain wherein an engagement between the elements attached to the element attaching portions is lost. Therefore, in general slide fasteners, the element attaching portion of the fastener tape is often constructed so as not to be stretchable.
Assume that a slide fastener in which a tape main portion of a fastener tape is constructed to be stretchable while an element attaching portion is constructed to be completely non-stretchable is attached to, for example, clothes having stretching property. In this case, when a user takes exercise such as stretching his or her body wearing that stretchable clothes, the element attaching portion is never stretched although the tape main portion is stretched or contracted corresponding to the stretching or contraction of the clothes. For the reason, there may occur such a fault that a pulling phenomenon occurs in a slide fastener attaching portion of the clothes or feeling of disharmony is induced on the appearance of the slide fastener when the user wears such clothes.
To solve such a fault, for example, Japanese Patent Application Laid-Open (JP-A) Publication No. 63-294804 has disclosed a slide fastener in which not only a tape main portion but also an element attaching portion surrounding portion is provided with stretching property. The slide fastener disclosed in JP-A-63-294804 has an elastic yarn (Spandex covered yarn) arranged regularly at specified intervals and a non-stretchable yarns disposed at other portions as warp yarns constituting the tape main portion and element attaching portion of the fastener tape. Further, a coil-like fastener element row in which a core thread is inserted internally is sewed to the element attaching portion of the fastener tape with a sewing thread. As the core thread, there is used a thread having a structure in which an elastic yarn is covered with a covering layer composed of a polyester bulky processed yarn (non-elastic yarn).
The slide fastener with such configuration disclosed in JP-A-63-294804 has a degree of stretching that the element attaching portion is stretched by 10% or more, for example, when a load of 4 kg is applied in the longitudinal direction of the fastener tape because the elastic yarns are disposed regularly at specified intervals on the element attaching portion like on the tape main portion.
On the other hand, a ratio of a quantity of the elastic yarns disposed in the element attaching portion is equal to that of the tape main portion. Further, a number of the non-elastic yarns are woven into the element attaching portion, the core thread is covered with the covering layer composed of the non-elastic yarns, so that a degree of stretching of the core thread itself is suppressed; and the fastener element row and the core thread are sewed to the element attaching portion with the non-elastic sewing thread. For this reason, a pitch between adjacent elements when the fastener stringer is stretched most is limited to be less than twice the length thereof in the tape longitudinal direction at a coupling head in the fastener element row.
Consequently, in the slide fastener of JP-A-63-294804, no pulling phenomenon or feeling of disharmony is generated when the slide fastener is attached to clothes having stretching property because the slide fastener attaching portion is stretched corresponding to the stretching/contraction of the clothes. This enables to improve feeling of wearing the clothes and to obtain excellent appearance. In addition, the element attaching portion of the fastener tape is provided with stretching property, and a maximum stretching amount of the fastener element row is limited as described above. As a result, occurrence of breaking of chain in the slide fastener due to loss of engagement of the fastener elements can be prevented for certain even if the element attaching portion is stretched.
In recent years, in a variety of clothes such as sporting clothes, the ones having a higher function have been demanded and developed to cope with an application and purpose. Currently, clothes having high stretching property whose fabric stretching property is further intensified have been marketed and spread.
On the other hand, the slide fastener disclosed in JP-A-63-294804 needs to be applied with a load of 4 kg in the longitudinal direction of the fastener tape to stretch the element attaching portion by 10% or more in the tape longitudinal direction. Assume that the slide fastener mentioned in JP-A-63-294804 whose element attaching portion has such a degree of stretching is used in highly stretchable clothes whose stretching property is intensified highly. If a load of less than 4 kg (for example, a load of about 1 kg) is applied, the highly stretchable clothes is stretched easily corresponding to its motion, but the slide fastener mentioned in JP-A-63-294804 does not have so sufficient stretching property allowing itself to follow up the motion of the highly stretchable clothes. For this reason, there are such faults that a pulling phenomenon occurs in the attaching portion of the slide fastener or feeling of remarkable disharmony is generated when wearing or on the appearance, and these problem need to be solved.